I’ve actually fielded requests from others looking for people willing to do this, so the demand is out there. To put it simply, some people are willing to pay others to get a vegetable or flower garden started for them in their yard so they can have access to ultra-fresh produce without all the legwork. If you have a green thumb and some knowledge about the vegetables that grow well in your area, this would be an easy business to start.
Not just via your old notes you can help your juniors by providing them with tutoring sessions, and make money with it. You can also choose the online tutoring option like Preply for earning money, in a subject with the number of views and download one gets. You can give tutoring lessons of some musical instrument or dance form, coaching is for anyone who holds cognition about something that people would be keen to learn. This is the best way to earn money, as I frequently discuss this in my write-ups. For every person there comes a different way of coaching, one can also become a home tutor. Many parents search for home tutors all the time.
Search for freelance writing and editing gigs. The rates for these jobs vary: you may be paid by the word, be offered a flat rate for a project, or in some cases can be paid an hourly rate. You typically won't be able to retain copyright over your work or collect royalties, however. Even so, by doing freelance work you can build a portfolio and make valuable connections which may later pay off with more stable job opportunities.